@JB77UK: thx for sharing the links. I haven't really spend much time thinking about it, but the half venturi never added up for me. It's not like the atmosphere is a gigantic other half of a venturi. Any why should there be some magic force requiring the molecules to meet again at the end of the flow ? In reality, they don't. The NASA explanation does absolutely make sense for me. It's basically Newton's second law of motion combined with the physical properties of a fluid.
Here's the whole "turning of a fluid" explanation:
Lift from Flow Turning